Fluid pressure switch utilizing an axially movable floating disk assembly



March 11. 1969 5. A. SCHERB 3,432,633

FLUID PRESSURE SWITCH UTILIZING AN AXIALLY MOVABLE FLOATING DISK ASSEMBLY Filed July 28, 1967 JNVENTOR. GUSTAI/E ,4. Sa /25,

United States Patent Claims Int. Cl. H0111 35/40 ABSTRACT OF THE DISCLOSURE A fluid pressure indicator switch which closes an alarm circuit when a pressure level transmitted to it drops below a prescribed norm. A flexible diaphragm normally closes the entrance into the switch housing, which is attached to a device having a pressurized chamber. The diaphragm rests against an axially floating disk assembly within the switch housing, biased toward the diaphragm by a coil spring under compression. Pressurized fluid is tapped from the pressurized chamber and impinged upon the diaphragm, which if normal, will enable the diaphragm to provide a suflicient force against the spring-biased floating disk assembly to prevent it from bridging a pair of electrical contacts in the switch housing to establish an electric circuit and sound an alarm. Should'the pressure be insuflicient, the circuit will be established.

This invention relates to a switch assembly, and more particularly, a fluid pressure indicator switch assembly for indicating a drop in pressure below a predetermined level in a device.

A fluid pressure indicator switch finds wide application in modern technology. For example, a device of the character described herein may be mounted on an airplane tire and any loss of tire pressure during flight can be quickly communicated to the pilot, who can make adequate preparations for it prior to landing. Any significant loss of pressure, whether the substance is water, air, oil or hydraulic fluid, can be detected by the switch.

Accordingly, it is an object of this invention to provide a self-contained fluid pressure indicator switch assembly having substantially universal application.

Another object of this invention is to provide a switch assembly of the character indicated with isolated contact elements extending from its housing for connection to any suitable detecting circuit.

Yet another object of this invention is to provide a switch assembly of the character indicated which comprises a simple construction and a minimum number of component parts, lending itself to economic manufacture.

Further objects and advantages of the invention will become apparent from the following description and claims, and from the accompanying drawing, wherein:

FIGURE 1 is a perspective view of the fluid pressure indicator switch assembly of the present invention;

FIGURE 2 is a cross-sectional view of the switch assembly of FIGURE 1, taken substantially along the plane indicated by line 2-2 of FIGURE 1, and further illustrating one mode of its use in phantom lines; and

FIGURE 3 is a cross-sectional view taken substantially along the plane indicated by line 33 of FIGURE 2.

Referring now to the drawing in detail, wherein like numerals indicate like elements throughout the several views, the switch assembly of the present invention is generally indicated by the numeral 10'.

Switch assembly 10 comprises a housing 12 formed from insulating material such as a hard plastic resin or a ceramic. Housing 12 includes an axial bore 14 therethrough terminating in enlarged diametrical portions or chambers 16 and 18 at its opposite ends.

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Molded integral with or otherwise attached to housing 12 are a pair of spaced electrical conductors 20 and22. Conductor 20 terminates at one end in an electrical contact point 24 exposed in chamber 16. At its other end, conductor 20 terminates in a rigid electrical tie point 26. Similarly, conductor 22 terminates at one end in an electrical contact point 28 exposed in chamber 16. At its other end, conductor 22 terminates in a rigid electrical tie point 30.

Suitable electric circuitry, including an alarm device can be connected in electrical series between tie points 26 and 30.

Housing 12 also includes an upper annular flange 32 and a lower annular flange 34. An annular top cap 36, provided with an annular inturned lip 38 is adapted to be snapped over flange 32 and be crimped to securely hold it in place. Depending from the center of top cap 36 is an annular cup 40 for a purpose to be described hereinafter.

An annular bottom cap 42, provided with an annular inturned tip 44 is adapted to be snapped over flange 34 and is crimped to securely hold it in place. Disposed and clamped between cap 42 and flange 34 is a thin, flexible rubber diaphragm 46 for a purpose to be described hereinafter. Cap 42 is also provided with an externally threaded stem 48 having an axial orifice 50 establishing communication between the exterior of cap 42 and diaphragm 46. Stern 48 is used to secure the switch assembly 10 to a pressurized chamber.

In abutment with diaphragm 46 within the interior of housing 12 is a floating disk assembly 52. Disk assembly 52 comprises a lower disk 54 in abutment with diaphragm 46 in chamber 18. Disk 54 has a stem 56 free to move vertically or float in axial bore 14. An upper disk 58 of conducting material is seated in chamber 16 on stem 56 of lower disk 54 by means of a depending stem 60 received with a bore 62 in stem 56, and a shoulder 61 in abutment with the top of stem 56. Disk 58 is of a suflicient diameter to bridge contact points 24 and 28 in chamber 16.

Disposed under compression between disk 58 and top cap 36, and confined laterally by annular cup 40, is a coil spring 64. Coil spring 64 normally biases disk 58 against stem 56, which in turn pushes lower disk 54 against diaphragm 46 and maintains floating disk assembly 52 captive.

In operation, threaded stem 48 is connected by a suitable adapter 66 to the valve structure 68 of a pressurized chamber, e.g., vehicle tire. The fluid under pressure in the chamber is conducted through orifice 50 and allowed to impinge on diaphragm 46.

Coil spring 64 is selected so that the normal fluid pressure impinging upon diaphragm 46 is suflicient to overcome the bias of the spring and maintain upper disk 58 in a raised position in chamber 16.

Should the pressure upon the diaphragm 46 fall below a predetermined norm, however, spring 64 will expand and push floating disk assembly '52 downwardly against diaphragm 46, until upper disk 58 bridges contact points 24 and 28. When disk 58 bridges contact points 24 and 28, an electrical circuit is established to actuate an alarm to indicate that a pressure loss has occurred in the pressurized chamber.

While a specific embodiment of my invention has been disclosed in the foregoing description, it will [be understood that various modifications within the spirit of the invention may occur to those skilled in the art. Therefore, it is intended that no limitations 'be placed on the invention except as defined by the scope of the appended claims.

I claim:

1. A fluid pressure indicator switch comprising a housing, means on said housing for securing it to a pressurized chamber, fluid inlet means into said housing, a flexible diaphragm in said housing covering said fluid inlet means, an axially 'movable floating disk assembly in said housing in abutment with said diaphragm, said disk assembly including an axially movable lower disk in abutment with said diaphragm and an axially movable upper electrically conductive disk connected to said lower disk, spring means within said housing in abutment with said upper :disk for biasing said disk assembly against said diaphragm, and spaced electrical contact means within said housing in the path of movement ofsaid upper disk.

2. A fluid pressure indicator switch in accordance with claim 1, wherein said spaced electrical contact means includes a pair of spaced contact points exposed within said housing, a pair of spaced electrical tie points projecting from said housing, and an electrical conductor connecting one of said tie points with one of said contact points.

3. A fluid pressure indicator switch in accordance with claim 1, wherein said securing means includes an externally threaded stern depending from said housing, and said fluid inlet means includes an orifice through said stem.

4. A fluid pressure indicator switch comprising a housing have an upper and lower annular flange at opposite ends thereof, said housing including an axial bore therethrough opening into diametrically enlarged upper and lower chambers at opposite ends thereof, a top cap secured to said upper annular flange to close said upper chamber, a lower cap secured to said lower annular flange to substantially close said lower chamber, said lower cap including a depending externally threaded stem, a fluid inlet orifice through said stem, a flexible diaphragm clamped between the lower flange of said housing and lower cap 4 and overlying said inlet orifice in said stem to close communication between said orifice and said lower chamber in said housing, an axially movable floating disk assembly in the axial bore of said housing, said disk assembly including an axially movable lower disk within said lower chamber in abutment with said diaphragm, an axially movable electrically conductive, upper disk in said upper chamber connected to said lower disk, spring means between said top cap and upper disk in said upper chamber for biasing said disk assembly against said diaphragm, and a pair of spaced electrical contact points exposed in said upper chamber in the path of movement of said upper disk.

5. A fluid pressure indicator switch in accordance with claim 4, wherein said housing is formed from electrically insulated material, a pair of spaced, rigid, electrical tie points projecting from said housing, and a pair of electrical conductors embedded in said housing connecting said tie points with said contact points.

References Cited UNITED STATES PATENTS 2,485,783 10/1949 Shaw 20081 2,566,545 9/ 1951 Alcoriza.

2,669,617 2/1954 Sletten et a1 200-81 XR 2,939,928 6/1960 Learn 20081.5 XR

FOREIGN PATENTS 291,513 6/ 1928 Great Britain.

ROBERT K. SCHAEFER, Primary Examiner.

H. BURKS, Assistant Examiner. 

